UPDATE: A flash flood warning for central Clark County was issued until 4 p.m. There were reports of heavy rain on the far west side of the valley from 1:30 p.m. until about 3 p.m. Some areas received dime-sized hail. In California along I-15, flooding was reported in the Nipton Road area (two exits west of Primm). Further south, I-40 at U.S. 95 was completely flooded for much of the afternoon. Conditions across much of the southwest could include heavy thunderstorms with the potential for flash flooding.LAS VEGAS (KSNV MyNews3.com) -- Much of Las Vegas received a good washing from Mother Nature on Sunday as heavy thunderstorms moved from west to east across the valley.

In Southern Nevada, the watch includes: Lake Mead National Recreation Area, the Las Vegas Valley, the Sheep Range, southern Clark County and the Spring Mountains including Red Rock Canyon.

The weather service report says a combination of daytime heating, abundant monsoon moisture and increasing instability will result in scattered thunderstorm activity into Sunday evening. The thunderstorms will be capable of producing rainfall amounts in excess of an inch in a very short time.

Normally dry washes and drainage channels may have elevated water levels at times today. Some roadways could become inundated and impassable. Motorists are reminded to turn around when they see water on the roads.

A flash flood watch means that conditions may develop that lead to flash flooding. Residents in and near the watch area should be alert to the potential for heavy rainfall.

The watch also includes the northwest deserts and northwest plateau in northwest Arizona as well as the eastern Mojave Desert in California.